The KWA KMP9 has been out for more than 2 years now and I want to know what changes have there been to the KWA KMP9 since its release, if any. Also I plan on getting it pretty soon, but don't know if I'll have to buy the low power bolt with it. I plan on using it for the first time in April, and the average temperature in Ohio in April is about 60-70, so will I need the bolt to shoot under 400 since I am below the age of 18. Thank you